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  1. Vitamins, dietary minerals and trace elements are essential to the healthy function of the human body. Vitamins are organic compounds that are vital to, but not always produced by, the body and so have to be obtained through the diet. Similarly, dietary minerals (e.g. calcium and phosphorous) and trace elements, of which even smaller amounts are required (e.g. zinc and selenium), are acquired through food. For the majority of people, a balanced, nutritious diet satisfies the body’s vitamin and mineral requirements.[1] There are two types of vitamins; fat soluble and water soluble. Fat soluble vitamins are found mainly in fatty foods and animal products, such as oils, butter, eggs, liver and oily fish. Whilst the body requires a constant supply of these vitamins, the tiny quantities needed coupled with their storage in the liver and fatty tissue for use when required mean that it is not vital to consume them every day. In fact large doses of fat soluble vitamins can be harmful. For example, the risk of lung and stomach cancers is increased in those who consume 20-30mg/day of B-carotene.[2] However many of the side effects seen with excess vitamin intake are not likely to happen as a result of dietary intake, but rather by exceeding the recommended dose with supplementation.[3], [4], [5]  Water soluble vitamins such as vitamin C, folic acid and niacin are found in a wide range of foods including vegetables, fruit, potatoes, grains and dairy food.[6] These water soluble vitamins are less stable than fat soluble vitamins. They are often destroyed by heat or air, meaning that they cannot be stored by the body and excesses are excreted in urine. The consumption of foods containing water soluble vitamins is therefore needed more often, to maintain the body’s supply. As they are excreted in the urine, water soluble vitamins are generally less harmful than fat soluble vitamins, although very high doses may have an adverse effect on the body.[7] For example, large doses vitamin C can cause diarrhoea,[8] while excess folic acid can have effects that range from abdominal cramps and nausea to confusion and increased seizure frequency.[9] Dietary minerals and trace elements have many functions including building strong bones and teeth, regulating the composition of the fluid inside and surrounding cells, and converting food to energy.[10] However high doses taken over a long period can be harmful, as demonstrated by the doubling of hospital admissions for gastrointestinal problems, 17% increase in kidney stones and 20-40% increase in the risk of a heart attack in those taking calcium supplements.[11] Despite the fact that a varied, healthy diet will provide adequate amounts of all essential vitamins, minerals and trace elements for most people, the use of dietary supplementation is increasing. There is no real evidence, that taking synthesised vitamins and mineral supplements has any real benefit to health. Furthermore, in addition to a lack of proven efficacy, the manufacture of dietary supplements is not regulated as stringently as that of medicines. This is because they are not classified as a food or a drug, and as such, they are not technically permitted to make any health claims. More worryingly, no clinical trials are required prior to their production and sale. Many supplements are manufactured by synthetic methods and contain additives such as sweeteners, which may be harmful to health, and they can interact with prescribed medications with serious and even life-threatening results.[12] In conclusion, naturally occurring vitamins and microelements are an important part of our diet. Whilst many synthetic supplements are available that contain high doses of these essential nutrients, it is often the case that our dietary intake is sufficient, except in cases of diseases or conditions that result in a vitamin deficiency. The potential for damaging effects seen with high intake of certain man made vitamins, coupled with the possibility for drug interactions means that you could be doing more harm than good by taking these ‘healthy’ supplements.   [1]  FAO/WHO (2001) Human vitamin and mineral requirements. Retrieved April 2016 from, [2]  Druesne-Pecollo N, et al. (2010) Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials.Int J Cancer. 127(1). 172-84. [3] Schwalfenberg, GK. & Genius, SJ. (2015) Vitamin D, Essential Minerals, and Toxic Elements: Exploring Interactions between Nutrients and Toxicants in Clinical Medicine.ScientificWorldJournal. 318595. [4]  Brown, AC. (2016) An overview of Herb and dietary supplement efficacy, safety and government regulations in the United States with suggested improvements. Part 1 of 5 series. Food Chem Toxicol. [epub ahead of print] doi: 10.1016/j.fct.2016.11.001. [5] Brown, AC. (2016) Liver toxicity related to herbs and dietary supplements: Online table of case reports. Part 3 of 6. Food Chem Toxicol. [epub ahead of print] doi: 10.1016/j.fct.2016.07.001. [6] CSU (2012) Water-soluble vitamins: B-complex and vitamin C. Retrieved November 2016 from, [7]  CSU (2012) Fat-soluble vitamins: A, D, E, and KB-complex and vitamin C. Retrieved November 2016 from, [8] Mulholland, CA, Benford, DJ. (2007) What is known about the safety of multivitamin-multimineral supplements for the generally healthy population? Theoretical basis for harm. Am J Clin Nutr. 85(1). 318S-322S [9] Rogovik, AL, Vohra, S, Goldman, RD. (2010) Safety considerations and potential interactions of vitamins: should vitamins be considered drugs? Ann Pharmacother. 44(2). 311-24. [10] Shenkin, A. (2006) Micronutrients in health and disease. Postgrad Med J. 82(971). 559-567. [11] Reid, IR, Bristow, SM, Bolland, MJ. (2015) Calcium supplements: benefits and risks. J Intern Med. 278(4). 354-68. [12] Williamson, EM. (2003) Drug-interactions between herbal and prescription medicines. Drug Saf. 26(15). 1075-92.  
  2. Although dietary supplements are not medicines, they still can have side effects based on volume consumed, thus you get warning about how much you can take of them daily, but I found the labels differing on given RDI. I wonder if there is any requirement of safety testing the dietary supplements before they end up on a supermarket shelf, please research and enlighten us.
  3. Much like prescription medicines, dietary supplements come with the potential for unwanted side effects. There are currently no requirements for clinical studies to verify the safety or even potency of a dietary supplement, as they are technically not allowed to claim any health benefits. Supplements also do not require a doctor’s prescription, making the vast majority of supplement use self-prescribed. This often means that people begin taking supplements without informed medical guidance. Many supplements contain active ingredients that can have varied and serious effects within the body, some desired, some not. In some cases, taking too much of a supplement can have serious complications. For example, some supplements can have unwanted effects before, during, and after surgery.[1] Supplements can also interact with prescription medicines to reduce or increase their activity, or to produce other unwanted side effects. Between 2008 and 2010, the American Association of Poison Control Centers (AAPCC) received 145,775 calls related to the side effects of dietary supplements, and the FDA (from 2008 to 2011) received 6,307 similar reports.[2] However even these numbers are still likely to dramatically underestimate the true scope of the situation, as most people suffering from unexpected side effects, illnesses, or drug interactions do not call a poison control centre or report the adverse reaction to the manufacturer of the supplement.  Potential supplement side effects can include gastrointestinal symptoms,[3]  liver toxicity,[4] heart attacks,[3] and even cancer.[5] Although these side effects can be serious and even fatal, consumers in general do not appreciate the risks. The use of the term “natural” on the product label often fools many into believing that the product is safe and can do them no harm, and the important ‘small print’ is often ignored. In addition to this, supplement manufacturers are not legally bound to indicate potential side effects on the product label. Increasingly popular diet and ‘muscle-building’ supplements can be some of the most dangerous. These types of supplements often contain stimulants which suppress the appetite, but which can also raise the blood pressure to dangerously high levels and increase the risk of a heart attack or stroke.[6] Whilst supplements can be beneficial to many users, individuals can react differently. Side effects can be experienced when using too high a dose of a product, when taking the recommended dose, or even when taking a less than recommended dose. Some supplements are marketed as having “almost no side effects”, but when combined with other substances, or taken too frequently, can quickly become toxic.[7] Vitamin C, for example, is often taken frequently to ‘boost’ the immune system, but taken in large amounts can cause diarrhoea. Other, more serious side effects are also possible - for example, the risk of lung and stomach cancers is significantly increased in those who consume 20-30mg/day of B-carotene.[8] In those taking calcium supplements, one study demonstrated a doubling of hospital admissions for gastrointestinal problems, a 17% increase in kidney stones and a 20-40% increase in the risk of a heart attack.[9] Once a side effect is found to be the result of dietary supplement intake in an individual, simply stopping taking the supplement will often lead to resolution of the side effect.[10] However this is not always the case, and some supplements can have longer-lasting effects, especially those with the potential for serious and even fatal side effects, such as cancer or increased risk of a heart attack.  Given this potential for serious and even fatal side effects, sound advice would be to think twice before opting to take dietary supplements and at the very least consulting your doctor before taking them, particularly if you are taking prescription medication. If, when taking supplements, you begin to develop side effects or symptoms, you should stop taking the supplement and consult your doctor before it is too late.   [1] Wang, CZ, Moss, J, Yuan, CS. (2015) Commonly Used Dietary Supplements on Coagulation Function during Surgery. Medicines (Basel). 2(3). 157-85. [2] GAO (2013) Dietary supplements FDA may have opportunities to expand its use of reported health problems to oversee products. Retrieved April 2016 from,  [3] Reid, IR, Bristow, SM, Bolland, MJ. (2015) Calcium supplements: benefits and risks. J Intern Med. 278(4). 354-68. [4] Haslan, H, Suhaimi, FH, Das, S. (2015) Herbal supplements and hepatotoxicity: a short review. Nat Prod Commun. 10(10). 1779-84. [5] Harvie, M. (2014) Nutritional supplements and cancer: potential benefits and proven harms. Am Soc Clin Oncol Educ Book. e478-86. [6] CDC (1996) Adverse events associated with ephedrine-containing products--Texas, December 1993-September 1995. MMWR Morb Mortal Wkly Rep. 45(32). 689-93. [7] Mulholland, CA, Benford, DJ. (2007) What is known about the safety of multivitamin-multimineral supplements for the generally healthy population? Theoretical basis for harm. Am J Clin Nutr. 85(1). 318S-22S. [8] Druesne-Pecollo N, et al. (2010) Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials.Int J Cancer. 127(1). 172-84. [9] Reid, IR, Bristow, SM, Bolland, MJ. (2015) Calcium supplements: benefits and risks. J Intern Med. 278(4). 354-68. [10] Felix, TM, Karpa, KD, Lewis, PR. (2015) Adverse effects of common drugs: dietary supplements. FP Essent. 436:31-40.  
  4. Drug interactions occur when the effect of a drug is altered if taken in conjunction with another drug, supplement, food, or alcohol. Drugs can interact with dietary supplements either directly or indirectly, increasing or decreasing the drug’s desired effects. Indirect effects can result from changes in excretion,  metabolism or, occasionally, absorption of the substance, which can result in reduced or increased pharmacological activity of the drug. This can trigger unexpected and potentially harmful side effects. These interactions can occur in numerous ways, from the way different substances react with each other in the stomach, to the mechanism of metabolism in the body. Such interactions can vary between subjects, as everyone’s body is different in terms of its ability to absorb, metabolise, distribute and excrete drugs and their metabolites. There are several factors that can lead to these differences, including genetic variation, body weight (hence why some drugs are dosed according to this), age, gender (often due to hormone levels), drug tolerance and even diet. An example of the latter is the reduced response to bronchodilators associated with a high-fat diet.[1] Because of these variations, drug interactions can be difficult to predict, even when their reactions are well-known.  Western populations consume an ever-increasing amount of dietary supplements, including vitamins, minerals, herbs and many other products. These can come in many forms, such as pills, capsules, powders, drinks and energy bars. Adverse reactions between supplements and prescribed medications are well documented: warfarin, insulin and aspirin, for instance, have a high record of adverse interactions with dietary or herbal supplements.[2] Mixing warfarin and fish oil, for example, can lead to uncontrolled bleeding, while insulin combined with chromium can induce hypoglycaemia in diabetics.[2] The increasing number of dietary supplements available, coupled with the fact that they are not as well-regulated as medicinal products, means the potential for adverse interactions is escalating. Consumers tend to assume that because dietary supplements are so readily available, they must be safe – a belief enhanced by the liberal use of the word ‘natural’ in association with these products. However, their safety is not necessarily assured, and their combined use with certain drugs can result in serious adverse reactions. Commonly used supplements such as vitamin E, ginseng and gingko biloba have all been touted for their ability to boost certain health aspects, but they also interact with various widely prescribed drugs, causing life-threatening reactions such as reduced blood clotting, psychosis, hypoglycaemia and even coma.[2] It is not just adverse reactions that are of concern when combining supplements and drugs. Interactions can also reduce a drug’s effectiveness, such as the interaction seen between St. John’s wort and oral contraceptive pills.[3] Consumers should always think carefully when choosing dietary supplements, especially those who are taking medications. The combination could potentially be lethal – a far cry from the aim of trying to improve your health. Always consult your doctor before taking a supplement or changing your medication regimen.   [1] Wood LG, Garg ML, Gibson PG (2011). A high-fat challenge increases airway inflammation and impairs bronchodilator recovery in asthma. J Allergy Clin Immunol. 127(5). 1133-40. [2] Gardiner P, Phillips R, Shaughnessy AF (2008). Herbal and dietary supplement-drug interactions in patients with chronic illnesses. Am Fam Physician. 77(1). 73-8. [3] Murphy PA, Kern SE, Stanczyk FZ, Westhoff CL (2005). Interaction of St. John's Wort with oral contraceptives: effects on the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding. Contraception. 71(6). 402-8.  
  5. What is healthy nutritional supplement There are two common misconceptions about dietary supplements: firstly that the more the better, and secondly that they can be taken to make up for a poor diet. Research into the value of supplements in both disease treatment and prevention is still ongoing, and there is often conflicting evidence associated with supplement intake.[1] [2] It seems increasingly clear that, despite scepticism, some supplements do have the potential to promote health by preventing certain diseases and conditions, but in other cases they can lead to serious side effects, including a suggestion that some may increase the risk of cancer.[2] For example, the risk of lung cancer in high risk populations is significantly increased in those who consume 20-30mg/day of B-carotene.[3] Another study showed a wide range of potentially damaging effects from taking calcium supplements, including the doubling of hospital admissions for gastrointestinal problems, 17% increase in kidney stones and 20-40% increase in the risk of a heart attack in those taking calcium supplements.[4] Dietary supplements can have specific benefits, though, for example it has long been known that taking folic acid during pregnancy reduces the development of birth defects.[5] The risks of developing certain diabetic complications such as heart disease and neuropathy are known to be reduced by taking supplements of omega-3 and alpha-lipoic acids.[6] [7] [8] There are also many severe medical conditions that are the direct result of nutrient deficiencies, possibly as the result of malabsorption, which can be reversed, or at least managed, by appropriate supplementation. These include bone fragility, anaemia, nervous system abnormalities and poor immune system functionality.[9] [10] [11] [12] Some deficiencies are actually classed as a condition in their own right (for example iron or vitamin B12 deficiencies). However, despite their potential beneficial effects, caution should be taken when using dietary supplements. As they are not classed as medicines or food, and thus they are not subject to the same manufacturing regulations as these products. Furthermore, due to insufficient evidence as to their impact on health, supplements should not legally make any claims regarding effects on health, although many do, and they are not officially intended to diagnose, treat, cure or prevent disease.[13] Supplements are therefore manufactured without the rigorous safety and efficacy testing demanded by law for any true medicinal product. In fact supplements are often manufactured from synthetic materials, such as hydrogenated sugar extracts or petrochemicals, and may contain genetically modified ingredients, artificial sweeteners and even carcinogenic substances.                                                       Some supplements are marketed as having “almost no side effects”, but when combined with other substances, or taken too frequently, can quickly become toxic. For example, large doses vitamin C or magnesium can cause diarrhoea, whereas excess iron intake is generally associated with constipation as well as abdominal pain, nausea and vomiting.[3] Worryingly, dietary supplements can also interact with prescribed medications with serious and even life-threatening results, e.g. warfarin, insulin and aspirin have many recorded adverse reactions when taken with dietary or herbal supplements.[14] In addition to these interactions, fat soluble vitamins such as vitamins A, D, E and K, can accumulate in the body if doses above the recommended daily limit are routinely taken. This toxicity can result in mental symptoms such as confusion[15] and physical symptoms, such as liver damage[16] and even death.[17]   There are many reason, to think twice about taking dietary supplements. There is a distinct lack of regulatory control, with none of the requirements that are required for medication approval in addition to the potential for adverse interactions with prescribed and over-the-counter medications. Far from being beneficial, some dietary supplements can actually cause serious harm when taken in excessive amounts or at the same time as other medications. The amount that is right for you will depend on numerous factors, and the recommended daily intake is not the one-size-fits-all that supplement manufacturers claim it is.   [1] The alpha-Tocopheral Beta Carotene Cancer Prevention Study Group. (1994) The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. N Engl J Med. 330. 1029-35. [2] Russo M, et al. (2016) Understanding genistein in cancer: The "good" and the "bad" effects: A review. Food Chem. 196. 589-600 [3] Mulholland, CA. & Benford, DJ. (2007) What is known about the safety of multivitamin-multimineral supplements for the generally healthy population? Theoretical basis for harm. Am J Clin Nutr. 85(1). 318S-322S [4] Reid, IR. et al. (2015) Calcium supplements: benefits and risks. J Intern Med. 278(4). 354-68. [5] CDC (1992) Recommendations for the Use of Folic Acid to Reduce the Number of Cases of Spina Bifida and Other Neural Tube Defects. Retrieved April 2016 from, [6] Midaoui, AEL. et al. (2002) Lipoic acid prevents hypertension, hyperglycaemia, and the increase in heart mitochondrial superoxide production. Am J Hypertens. 16(3). 173-9 [7] Jeppensen, C. et al. (2013) Omega-3 and omega-6 fatty acids and type 2 diabetes. Curr Diab Rep. 13(2). 279-88. [8] Evans, JL. & Bahng, M. (2000) Non-pharmaceutical intervention options for Type 2 Diabetes: Diets and dietary supplements (Botanicals, antioxidants, and minerals). South Dartmouth (MA): Endotext. [9] Wizenberg, T. et al. (2012) Vitamin D and the musculoskeletal health of older adults. Aust Fam Physician. 41(3). 92-9. [10] Shipton, MJ. & Thachil, J. (2015) Vitamin B12 deficiency - A 21st century perspective. Clin Med (Lond). 15(2). 145-50. [11] Mpandzou, G. et al. (2016) Vitamin D deficiency and its role in neurological conditions: A review. Rev Neurol (Paris). 172(2). 109-22. [12] Spinas, E. et al. (2015) Crosstalk between vitamin B and immunity.  J Biol Regul Homeost Agents. 29(2). 283-8. [13] Camire, ME. & Kantor, MA. (1999) Dietary supplements: nutritional and legal considerations. Food Techonol. 53(7). 87-96. [14] Tsai, HH. et al. (2012) Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review. Int J Clin Prac. 66(11). 1056-78. [15] Maji, D. (2012) Vitamin D toxicity. Indian J Endocrinol Metab. 16(2). 295-6. [16] Castaño G. et al. (2006) Vitamin A toxicity in a physical culturist patient: a case report and review of the literature. Ann Heptaol. 5(4). 293-95. [17] de Oliveira, MR. (2015) Vitamin A and retinoids as mitochondrial toxicants. Oxid Med Cell Longev. [epub] doi: 10.1155/2015/140267.